ZEILEIS, A.; KLEIBER, C.; JACKMAN, S. Regression Models for Count Data in R. Journal of Statistical Software, [S. l.], v. 27, n. 8, p. 1–25, 2008. DOI: 10.18637/jss.v027.i08. Disponível em: https://www.jstatsoft.org/index.php/jss/article/view/v027i08. Acesso em: 9 dec. 2021.